This represents an HTTP/2 connection from a client to Tomcat. It is designed
on the basis that there will never be more than one thread performing I/O at
a time.
For reading, this implementation is blocking within frames and non-blocking
between frames.
Note:

You will need to nest an <UpgradeProtocol
className="org.apache.coyote.http2.Http2Protocol" /> element inside
a TLS enabled Connector element in server.xml to enable HTTP/2 support.